Congenital heart defects may be caused by a single, simple malformation which produces severe secondary problems. By operating on the fetus, these secondary problems may be avoided. However, fetal tissues are far more fragile than postnatally, and conventional surgical approaches cannot be used as the sutures pull through the tissues. Providing a hemostatic and strong bond between tissues by using laser welding technology may allow repairs to be made thereby making fetal cardiac surgery a reality. Further, laser assisted hemostasis will prevent hemorrhage which will be a major risk factor to the fetus. By comparing conventionally sutured anastomoses to laser assisted or laser welded anastomoses, the strength and fluid integrity of the weld will be defined. The validity of laser technology for fetal vascular anastomotic applications will be determined. Phase I feasibility studies will include both in vitro and in vivo experiments. Spectroscopic measurement on fetal tissue will guide the selection of laser wavelength. Both temperature and optical feedback methods will be explored for controlling the laser in order to produce strong tissue bonds. Tissue solders will be evaluated to enhance tissue welding and hemostasis. In Phase II, sensor control of the laser, based on a tissue signature change at the welding endpoint, will be designed and developed, specifically for this application. PROPOSED COMMERCIAL APPLICATION: The development of fetal vascular anastomotic procedures using laser welding technology may be applicable to heart bypass surgery in adults, emergency would closure and hemostasis.